docs: def authenticate(json_path=None):
    """Gets a Natural Language API parser by authenticating the API.
  
    **This method is deprecated.** Please use :obj:`budou.get_parser` to obtain a
    parser instead.
  
    Args:
      json_path (:obj:`str`, optional): The file path to the service account's
          credentials.
  
    Returns:
      Parser. (:obj:`budou.parser.NLAPIParser`)
  
    """
    msg = ('budou.authentication() is deprecated. '
           'Please use budou.get_parser() to obtain a parser instead.')
    warnings.warn(msg, DeprecationWarning)
    parser = get_parser('nlapi', credentials_path=json_path)
    return parser